No-Dose Photodynamic Therapy Against Half-Dose Photodynamic Therapy for Treatment of Central Serous Chorioretinopathy

INTRODUCTION

This study aimed to describe the effects of no-dose full-fluence photodynamic therapy without verteporfin (no-dose PDT) and to compare no-dose PDT with half-dose verteporfin full-fluence photodynamic therapy (HDFF PDT) for managing chronic central serous chorioretinopathy (cCSC).

METHODS

This retrospective study evaluated 11 patients with chronic recurrent CSC treated with no-dose PDT between January 2019 and March 2022. Most of these patients were also treated with HDFF PDT a minimum of 3 months before and were considered as the control group. We described the changes of best corrected visual acuity (BCVA), maximum subretinal fluid (mSRF), foveal subretinal fluid (fSRF), and choroidal thickness (CT) 8 ± 2 weeks after no-dose PDT, and we compared BVCA, mSRF, fSRF, and CT of no-dose PDT with those of the of same patients previously treated with HDFF PDT.

RESULTS

Fifteen eyes of 11 patients (10 male, mean age 54 ± 12 years) received no-dose PDT; among these, 10 eyes of 8 patients (7 male, mean age 53 ± 12 years) also received HDFF PDT. Three eyes showed complete resolution of fSRF after no-dose PDT. No significant differences were disclosed between treatment with and without verteporfin comparing BCVA, mSRF, fSRF, and CT at baseline and 8 ± 2 weeks from the treatment (p > 0.05 in all analyses).

CONCLUSION

BVCA and CT significantly improved after no-dose PDT. Short-term functional and anatomical treatment outcomes for cCSC were similar for HDFF PDT and no-dose PDT. We hypothesize that the potential benefits of no-dose PDT may arise from thermal elevation that triggers and enhances photochemical activities by endogenous fluorophores, activating a biochemical cascade response that rescues/replaces sick, dysfunctional retinal pigment epithelial (RPE) cells. Results of this study suggest the potential value of a prospective clinical trial to evaluate no-dose PDT for managing cCSC, especially when verteporfin is contraindicated or unavailable.

A hollow Co3-xCuxS4 with glutathione depleting and photothermal properties for synergistic dual-enhanced chemodynamic/photothermal cancer therapy

Chemodynamic therapy has become an emerging cancer treatment strategy, in which tumor cells are killed through toxic reactive oxygen species (ROS), especially hydroxyl radicals (˙OH) produced by the Fenton reaction. Nevertheless, low ROS generation efficiency and ROS depletion by cellular antioxidant systems are still the main obstacles in chemodynamic therapy. In the present work, we propose a dually enhanced chemodynamic therapy obtained by inhibiting ˙OH consumption and promoting ˙OH production based on the administration of bimetallic sulfide Co_3-xCu_xS₄ nanoparticles functionalized by polyethylene glycol. These bimetallic nanoparticles display glutathione depleting and photothermal properties. The nanoparticles are gradually degraded in a tumor microenvironment, resulting in Co²⁺ and Cu²⁺ release. The released Co²⁺ triggers a Fenton-like reaction that turns endogenous hydrogen peroxide into highly toxic ˙OH. In the cellular environment, Cu²⁺ ions are reduced to Cu⁺ by endogenous GSH, which decreases the intracellular antioxidant capacity and additionally up-regulates ˙OH production via the Cu⁺-induced Fenton-like reaction. Moreover, under near-infrared light irradiation, the bimetallic nanoparticles display a photothermal conversion efficacy of 46.7%, which not only improves chemodynamic therapy via boosting a Fenton-like reaction but results in photothermal therapy through hyperthermia. Both in vitro cancer cell killing and in vivo tumor ablation experiments show that the bimetallic nanoparticles display outstanding therapeutic efficacy and negligible systemic toxicity, indicating their anticancer potential.

The Age-Related Macular Degeneration (AMD)-Preventing Mechanism of Natural Products

Age-related macular degeneration (AMD) is related to central visual loss in elderly people and, based on the increment in the percentage of the aging population, the number of people suffering from AMD could increase. AMD is initiated by retinal pigment epithelium (RPE) cell death, finally leading to neovascularization in the macula lutea. AMD is an uncurable disease, but the symptom can be suppressed. The current therapy of AMD can be classified into four types: device-based treatment, anti-inflammatory drug treatment, anti-vascular endothelial growth factor treatment, and natural product treatment. All these therapies have adverse effects, however early AMD therapy used with products has several advantages, as it can prevent RPE cell apoptosis in safe doses. Cell death (apoptosis) is caused by various factors, such as oxidative stress, inflammation, carbonyl stress, and a deficiency in essential components for cells, and RPE cell death is related to oxidative stress, inflammation, and carbonyl stress. Some natural products have anti-oxidative effects, anti-inflammation effects, and/or anti-carbonylation effects. The AMD preventive mechanism of natural products varies, with some natural products activating one or more anti-apoptotic pathways, such as the Nrf2/HO-1 anti-oxidative pathway, the anti-inflammasome pathway, and the anti-carbonyl pathway. As AMD drug candidates from natural products effectively inhibit RPE cell death, they have the potential to be developed as drugs for preventing early (dry) AMD.

Medication Trends for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is central vision loss with aging, was the fourth main cause of blindness in 2015, and has many risk factors, such as cataract surgery, cigarette smoking, family history, hypertension, obesity, long-term smart device usage, etc. AMD is classified into three categories: normal AMD, early AMD, and late AMD, based on angiogenesis in the retina, and can be determined by bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E)-epoxides from the reaction of A2E and blue light. During the reaction of A2E and blue light, reactive oxygen species (ROS) are synthesized, which gather inflammatory factors, induce carbonyl stress, and finally stimulate the death of retinal pigment epitheliums (RPEs). There are several medications for AMD, such as device-based therapy, anti-inflammatory drugs, anti-VEGFs, and natural products. For device-based therapy, two methods are used: prophylactic laser therapy (photocoagulation laser therapy) and photodynamic therapy. Anti-inflammatory drugs consist of corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs). Anti-VEGFs are classified antibodies for VEGF, aptamer, soluble receptor, VEGF receptor-1 and -2 antibody, and VEGF receptor tyrosine kinase inhibitor. Finally, additional AMD drug candidates are derived from natural products. For each medication, there are several and severe adverse effects, but natural products have a potency as AMD drugs, as they have been used as culinary materials and/or traditional medicines for a long time. Their major application route is oral administration, and they can be combined with device-based therapy, anti-inflammatory drugs, and anti-VEGFs. In general, AMD drug candidates from natural products are more effective at treating early and intermediate AMD. However, further study is needed to evaluate their efficacy and to investigate their therapeutic mechanisms.

Retinal temperature determination based on photopic porcine electroretinogram

OBJECTIVE

Subthreshold retinal laser therapy (SLT) is a treatment modality where the temperature of the retinal pigment epithelium (RPE) is briefly elevated to trigger the therapeutic benefits of sublethal heat shock. However, the temperature elevation induced by a laser exposure varies between patients due to individual differences in RPE pigmentation and choroidal perfusion. This study describes an electroretinography (ERG)-based method for controlling the temperature elevation during SLT.

METHODS

The temperature dependence of the photopic ERG response kinetics were investigated both ex vivo with isolated pig retinas and in vivo with anesthetized pigs by altering the temperature of the subject and recording ERG in different temperatures. A model was created for ERG-based temperature estimation and the feasibility of the model for controlling SLT was assessed through computational simulations.

RESULTS

The kinetics of the photopic in vivo flash ERG signaling accelerated between 3.6 and 4.7%/C, depending on the strength of the stimulus. The temperature dependence was 5.0%/C in the entire investigated range of 33 to 44C in ex vivo ERG. The simulations showed that the method is suitable for determining the steady-state temperature elevation in SLT treatments with a sufficiently long laser exposure and large spot size, e.g., during > 30 s laser exposures with > 3 mm stimulus spot diameter.

CONCLUSIONS

The described ERG-based temperature estimation model could be used to control SLT treatments such as transpupillary thermotherapy.

SIGNIFICANCE

The introduced ERG-based method for controlling SLT could improve the repeatability, safety, and efficacy of the treatment of various retinal disorders.

The Question of a Role for Statins in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in patients over the age of 65 years in industrialized countries. Epidemiologic studies suggest that high dietary fat intake is a risk factor for the development and progression of both vascular and retinal disease. These, and other associations, suggest a hypothesis linking elevated cholesterol and AMD progression. It follows, therefore, that cholesterol-lowering medications, such as statins, may influence the onset and progression of AMD. However, the findings have been inconclusive as to whether statins play a role in AMD. Due to the significant public health implications of a potential inhibitory effect of statins on the onset and progression of AMD, it is important to continually evaluate emerging findings germane to this question.

Evolution of Concepts and Technologies in Ophthalmic Laser Therapy

Ophthalmology was the first medical specialty to adopt lasers right after their invention more than 50 years ago, and they gradually revolutionized ocular imaging, diagnostics, therapy, and surgery. Challenging precision, safety, and selectivity requirements for ocular therapeutic and surgical procedures keep advancing the laser technologies, which in turn continue enabling novel applications for the preservation and restoration of sight. Modern lasers can provide single-cell-layer selectivity in therapy, submicrometer precision in three-dimensional image-guided surgery, and nondamaging retinal therapy under optoacoustic temperature control. This article reviews the evolution of laser technologies; progress in understanding of the laser-tissue interactions; and concepts, misconceptions, and accidental discoveries that led to modern therapeutic and surgical applications of lasers in ophthalmology. It begins with a brief historical overview, followed by a description of the laser-tissue interactions and corresponding ophthalmic applications.

A Novel Method for Mouse Retinal Temperature Determination Based on ERG Photoresponses

This study introduces a novel retinal temperature determination method based on the temperature dependent properties of photoresponses recorded by electroretinography (ERG). The kinetics and amplitudes of ERG photoresponses depend on retinal temperature. Additionally, raising retinal temperature increases the probability of long-wavelength photon absorption, which manifests as temperature dependence of photoreceptor sensitivity. In this study we extract a number of features that represent these properties from the a- and b-waves of mouse ex vivo ERG flash responses and construct three multivariable regression models between temperature and the selected features. The performance of these models was evaluated against a separate test dataset and for two of the models, an RMS temperature determination error of less than 0.50 °C could be reached. Our results demonstrate that the method can be successfully used for reliable retinal temperature determination ex vivo. The method, reflecting the temperature of distal retina, can be applied also in the estimation of retinal pigment epithelium temperature.

Retinal safety of near infrared radiation in photovoltaic restoration of sight

Photovoltaic restoration of sight requires intense near-infrared light to effectively stimulate retinal neurons. We assess the retinal safety of such radiation with and without the retinal implant. Retinal damage threshold was determined in pigmented rabbits exposed to 880nm laser radiation. The 50% probability (ED50) of retinal damage during 100s exposures with 1.2mm diameter beam occurred at 175mW, corresponding to a modeled temperature rise of 12.5°C. With the implant, the same temperature was reached at 78mW, close to the experimental ED50 of 71mW. In typical use conditions, the retinal temperature rise is not expected to exceed 0.43°C, well within the safety limits for chronic use.

Protective effect of a laser-induced sub-lethal temperature rise on RPE cells from oxidative stress

Recently introduced new technologies that enable temperature-controlled laser irradiation on the RPE allowed us to investigate temperature-resolved RPE cell responses. In this study we aimed primarily to establish an experimental setup that can realize laser irradiation on RPE cell culture with the similar temperature distribution as in the clinical application, with a precise time/temperature history. With this setup, we conducted investigations to elucidate the temperature-dependent RPE cell biochemical responses and the effect of transient hyperthermia on the responses of RPE cells to the secondary-exposed oxidative stress. Porcine RPE cells cultivated in a culture dish (inner diameter = 30 mm) with culture medium were used, on which laser radiation (λ = 1940 nm, spot diameter = 30 mm) over 10 s was applied as a heat source. The irradiation provides a radially decreasing temperature profile which is close to a Gaussian shape with the highest temperature in the center. Power setting for irradiation was determined such that the peak temperature (Tmax) in the center of the laser spot at the cells reaches from 40 °C to 58 °C (40, 43, 46, 50, 58 °C). Cell viability was investigated with ethidium homodimer III staining at the time points of 3 and 24 h following laser irradiation. Twenty four hours after laser irradiation the cells were exposed to hydrogen peroxide (H2O2) for 5 h, followed by the measurement of intracellular glutathione, intracellular 4-hydroxynonenal (HNE) protein adducts, and secreted vascular endothelial growth factor (VEGF). The mean temperature threshold for RPE cell death after 3 h was found to be around 52 °C, and for 24 h around 50 °C with the current irradiation setting. A sub-lethal preconditioning on Tmax = 43 °C significantly induced the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio, and decreased H2O2-induced increase of intracellular 4-HNE protein adducts. Although sub-lethal hyperthermia (Tmax = 40 °C, 43 °C, and 46 °C) caused a slight increase of VEGF secretion in 6 h directly following irradiation, secondary exposed H2O2-induced VEGF secretion was significantly reduced in the sub-lethally preheated groups, where the largest effect was seen following the irradiation with Tmax = 43 °C. In summary, the current results suggest that sub-lethal thermal laser irradiation on the RPE at Tmax = 43 °C for 10 s enhances cell defense system against oxidative stress, with increasing the GSH/GSSG ratio. Together with the results that the decreased amount of H2O2-induced 4-HNE in sub-lethally preheated RPE cells was accompanied by the lower secretion of VEGF, it is also strongly suggested that the sub-lethal hyperthermia may modify RPE cell functionality to protect RPE cells from oxidative stress and associated functional decrease, which are considered to play a significant role in the pathogenesis of age-related macular degeneration and other chorioretinal degenerative diseases.

Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture

PURPOSE

To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD.

DESIGN

Review of published clinical and experimental studies.

METHODS

Analysis and synthesis of clinical and experimental data.

RESULTS

We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors.

CONCLUSIONS

Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.

Red laser cyclophotocoagulation in the treatment of secondary glaucoma in eyes with uveal melanoma

PURPOSE

To evaluate retrospectively the usefulness of the red diode and krypton laser for transscleral contact cyclophotocoagulation (CPC) in the treatment of secondary glaucoma in eyes with uveal melanoma.

PATIENTS AND METHODS

Twenty-seven eyes of 27 patients (mean age, 66 y; range, 33 to 85 y) with a uveal melanoma and secondary glaucoma were treated with a transscleral 670-nm diode (40 treatments) and 647-nm krypton (5 treatments) laser CPC; 25 eyes had been or were subsequently treated with brachytherapy. The energy used was 420 mW at the tip of the probe (exposure time, 10 s). Seventeen eyes were treated once, 6 eyes twice, and 4 eyes 3 to 6 times. The aim was to preserve vision in 21 patients and to relieve pain in 6 patients. Fourteen patients (52%) died during follow-up.

RESULTS

With ≥1 CPCs, the intraocular pressure decreased from a median of 40 mm Hg at baseline to 28 mm Hg at 12 months (n=18) and 23 mm Hg at 24 months (n=10). Hypotony developed in 6 eyes. Before CPC, 12 eyes had a best corrected visual acuity (BCVA) of 20/400 or better. At 12 months, 5 of 18 eyes had BCVA 20/400 or better, and at 24 months 4 of 10 eyes. Four eyes were removed. At the latest visit, 15 of 23 eyes had no light perception, but were preserved. All patients whose aim of treatment was to relieve pain achieved pain relief.

CONCLUSIONS

CPC lowered intraocular pressure and the number of medications needed for secondary glaucoma in eyes with uveal melanoma, also providing pain relief.

Regression of peripapillary choroidal neovascularization after oscillatory transpupillary thermotherapy and anti-VEGF pharmacotherapy

PURPOSE

We prospectively evaluated a new treatment for recalcitrant choroidal neovascularization (CNV) in 4 patients. We used an infrared laser (810 nm) in oscillatory thermotherapy (OTT) mode combined with indocyanine green (ICG) dye, utilizing the beneficial effect of both thermotherapy and photodynamic therapy. We describe preliminary experiences with ICG-assisted OTT (I-OTT) combined with intravitreal bevacizumab/dexamethasone for refractory peripapillary CNV resistant to standard therapy.

METHODS

Clinical examination, funduscopy, fluorescein angiography, and optical coherence tomography were performed at baseline and postoperatively. Infrared laser spot size was approximately one-half the lesion size (oscillation 2-3 Hz). Intravitreal injections of bevacizumab (1.25 mg) and dexamethasone (1000 µg) were done during the same visit.

RESULTS

Mean follow-up was 12.5 months (range 5-17). Mean energy level was 325 mW (range 200-500) in oscillatory mode (2-3 Hz/sec) pre- and post-ICG infusion. Indocyanine green dose was approximately 1 mg/kg (75 mg/patient). All patients had a single treatment. Mean visual acuity improved in 1 patient from 20/60 to 20/30 and remained the same in the other 3 (20/20, 20/40, and 20/400). At final examination, there was no evidence of clinical or angiographic activity of CNV.

CONCLUSIONS

Indocyanine green-assisted OTT has the potential to treat CNV in wet age-related macular degeneration. It may reduce thermal side effects and eliminate or reduce the need for frequent intravitreal treatment. We postulate that I-OTT has a synergistic effect of thermal energy combined with a weak photosensitizer (ICG) applied in an individualized manner, which minimizes thermal damage to retinal and choroidal tissue. Additional anti-vascular endothelial growth factor pharmacotherapy enhances the effect of I-OTT on abnormal new vessels.

Detection of heat shock protein 70 in choroidal neovascular membranes secondary to age related macular degeneration

Background

Heat shock proteins are acute phase proteins that are upregulated in inflammation or following thermal stress. We analyzed the presence of the heat shock protein 70 (Hsp 70) in choroidal neovascular (CNV) membranes secondary to AMD after treatment with verteporphin photodynamic therapy (PDT) or transpupillary thermo therapy (TTT) to determine whether treatment correlated with the presence of Hsp70.

Results

CNV membranes were removed by pars plana vitrectomy (ppV) and subretinal extraction. The membranes were analysed by light microscopy and the presence of Hsp 70 was examined using histochemistry. HeLa Cells served as controls.

Of the 14 membranes analysed 11 were Hsp70 positive and 3 negative. In the no pre-treatment group of 8 membranes 6 were Hsp70 positive and 2 negative; in the PTD group all 4 membranes were positive and in the TTT group 1 membrane was positive and 1 membrane was negative for Hsp70.

Conclusion

Hsp70 is present in the most CNV membranes secondary to AMD. Pre-treatment of the membrane with PTD or TTT does not appear to influence the expression of Hsp70.

Long-term SD-OCT/SLO imaging of neuroretina and retinal pigment epithelium after subthreshold infrared laser treatment of drusen

PURPOSE

The purpose of this study was to determine the long-term effect of subthreshold diode laser treatment for drusen in patients with nonexudative age-related macular degeneration with spectral domain optical coherence tomography combined with simultaneous scanning laser ophthalmoscope.

METHODS

Eight eyes of four consecutive age-related macular degeneration patients with bilateral drusen previously treated with subthreshold diode laser were imaged with spectral domain optical coherence tomography/scanning laser ophthalmoscope. Abnormalities in the outer retinal layers' reflectivity as seen with spectral domain optical coherence tomography/scanning laser ophthalmoscope were retrospectively analyzed and compared with color fundus pictures, and autofluorescence images were acquired immediately before and after the laser treatment.

RESULTS

A focal discrete disruption in the reflectivity of the outer retinal layers was noted in 29% of the laser lesions. The junction in between the inner and outer segment of the photoreceptor was more frequently affected, with associated focal damage of the outer nuclear layer. Defects of the retinal pigment epithelium were occasionally detected. These changes did not correspond to threshold burns on color fundus photography but corresponded to focal areas of increased autofluorescence in the majority of the cases.

CONCLUSION

Subthreshold diode laser treatment causes long-term disruption of the retinal photoreceptor layer as analyzed by spectral domain optical coherence tomography/scanning laser ophthalmoscope. The concept that subthreshold laser treatment can achieve a selected retinal pigment epithelium effect without damage to rods and cones may be flawed.

Effect of polarized light emitting diode irradiation on wound healing

BACKGROUND

We propose a new phototherapy using polarized light from light emitting diode (LED). The purpose of this study is to clarify the effect of polarized LED irradiation on wound healing.

METHODS

Five groups were classified: control (C), unpolarized (U), linearly polarized (L), right circularly polarized (RC), and left circularly polarized (LC) LED irradiation. In vitro study, fibroblast cell cultures were irradiated, and cellular proliferation was evaluated with a WST-8 assay. In vivo study, full-thickness skin defect of 20 mm diameter was created on the dorsal side of rats. The ratio of the residual wound area was measured, and expression of type 1 and type 3 procollagen mRNA in granulation tissue was determined by real-time reverse transcription polymerase chain reaction method.

RESULTS

The cellular proliferation rates of group RC and L were significantly higher than other groups. The ratio of the residual wound area of group RC and L was significantly reduced than group C and U. Expression of type 1 procollagen mRNA in group RC was found to be significantly increased about 1.5-fold in comparison with the group C. There were no significant differences for type 3 procollagen.

CONCLUSIONS

The right circularly polarized light and linearly polarized light promoted the process of wound healing by increasing the proliferation of fibroblasts, and the right circularly polarized light increased the expression of type 1 procollagen mRNA. The effectiveness of right circularly polarized light suggests that some optical active material, which has a circular dichroic spectrum, takes part in a biochemical reaction.

Fluorescein and indocyanine green angiography after transpupillary thermotherapy of choroidal neovascularization. Early vascular changes

Transpupillary thermotherapy (TTT) is currently being evaluated in clinical trials for the treatment of choroidal neovascularization (CNV). Preliminary results show that TTT achieves closure of CNV and reduction in subretinal exudation while preserving visual acuity. Fluorescein and indocyanine green angiography reveal increased leakage activity from CNV and collateral choroid within 1 hour after TTT and absence of dye leakage from CNV at 1 week after treatment. Optical coherence tomography confirms the angiographic findings. The early vascular changes after TTT of CNV are similar to those observed after PDT of CNV. Transpupillary thermotherapy and PDT might share common mechanisms of action. A placebo-controlled, multi-center trial (TTT4CNV) evaluating the long-term efficacy and visual implications of TTT in occult CNV is underway.

Efficacy of transpupillary thermotherapy (TTT) in the treatment of occult subfoveal choroidal neovascularization in age-related macular degeneration

PURPOSE

To determine the efficacy of transpupillary thermotherapy (TTT) in the treatment of occult subfoveal choroidal neovascularization in patients with age-related macular degeneration (ARMD).

METHODS

We conducted a retrospective review of patients with ARMD treated with TTT from June, 1999 through July, 2000 at a retina referral practice. TTT was delivered through a slit-lamp using a modified diode laser at 810 nm wavelength and a spot size of 3 mm delivered at one location for a minimum of 60 seconds duration. Re-treatment was performed at 2-month intervals if indicated.

RESULTS

81 eyes of 77 patients were included in the study. Vision improved greater than one line Snellen in 18 eyes (22%), vision was stable within one line Snellen in 38 (47%), and worsened greater than one line Snellen in 25 (31%). Patients had a mean follow-up of 9 months. The average number of treatments was 1.37 (range 1 to 4). Pretreatment vision was less than or equal to 20/200 in 54% of eyes.

CONCLUSIONS

Transpupillary thermotherapy may stabilize visual acuity in a majority of patients with occult subfoveal choroidal neovascularization secondary to ARMD. Proof of therapeutic benefit is best determined by a randomized clinical trial that is currently underway (TTT4CNV).

Ophthalmoscopic contact lenses for transpupillary thermotherapy

Ophthalmoscopic contact lenses for transpupillary thermotherapy (TTT) must provide effective visualization of retinal treatment sites and transmission of infrared diode laser radiation. Selection and proper use of retinal laser lenses requires knowledge of their lateral magnification, laser beam magnification factor, field of view and resolution. Optical performance is analyzed for Goldmann-type lenses and a series of inverted image lenses of differing magnification. Goldmann lenses have the highest resolution, but inverted image lenses of comparable magnification have 2.5 times or more their field of view. Inverted image lenses of similar magnification can differ in resolution. They require 2-4% more incident laser power to produce the same retinal irradiance as a Goldmann lens, but this difference is small in comparison to other clinical variables. Tilting an ophthalmoscopic contact lens up to 15 degrees causes little distortion in the circularity of the retinal spot formed by a laser beam or difference in retinal irradiance across the spot. Inverted image lenses produce higher anterior segment irradiances than Goldmann-type lenses, but anterior segment injuries are less likely in TTT than conventional visible light, short-pulse retinal photocoagulation because of the comparatively low irradiances used in TTT and the decreased absorption of diode laser infrared radiation in ocular media and melanin.

Transpupillary thermotherapy (TTT) of occult choroidal neovascularization: A retrospective, noncomparative case series of fifty-seven eyes

PURPOSE

To evaluate the efficacy of transpupillary thermotherapy (TTT) for the treatment of occult choroidal neovascularization.

METHODS

A retrospective, noncomparative case series of 57 eyes of 52 patients who presented with occult subfoveal CNV and were treated with TTT.

RESULTS

83% of eyes were either stable (+/- one line) or showed improvement in visual acuity. 83% of eyes showed stabilization of their exudative process after one TTT treatment as evidenced by resorption of subretinal and/or intraretinal exudate or hemorrhage. Nine percent of eyes developed classic CNV during the mean follow-up time of ten months.

CONCLUSIONS

TTT appears to stabilize the exudative process in eyes with occult CNV. A prospective, sham-controlled, randomized study (TTT4CNV Clinical Trial) is currently underway to directly compare TTT to the natural history of occult CNV.

Transpupillary thermotherapy (TTT) for age-related macular degeneration

PURPOSE

To review the results of transpupillary thermotherapy (TTT) on choroidal neovascular membranes associated with age-related macular degeneration (AMD).

MATERIALS AND METHODS

35 eyes of 35 patients with AMD and choroidal neovascularization and exudation were treated with TTT and had fundus photographs and fluorescein angiography (FA) before and at least six months after TTT. 28 eyes had predominantly occult lesions as seen on FA, while 7 demonstrated primarily classic lesions. All were treated with 650mw power or less using the 810 nm diode laser (3000 micron spot, duration of 60 seconds). Visual acuity, lesion size, and amount of subretinal fluid were determined by results of examination and review of photographs and fluorescein angiograms.

RESULTS

A 50% reduction in subretinal fluid was achieved in 67% of treated eyes overall, with stabilization of vision (less than three lines of visual acuity lost) in 86%. Complications from treatment were infrequent (9%) and involved hemorrhage noted in the region of treatment upon follow-up.

CONCLUSION

TTT promotes resolution of subretinal fluid and appears to stabilize visual acuity in patients with exudative AMD.

Transpupillary thermotherapy for age-related macular degeneration: Principles and techniques

Transpupillary thermotherapy (TTT) is a subthreshold, low irradiance, long exposure duration, large spot size, infrared diode laser protocol. Retinal temperature increases in TTT for choroidal neovascularization (CNV) are substantially lower than those in conventional short-pulse photocoagulation, but they are maintained for 60 seconds to achieve therapeutic results. Treatment power is adjusted for retinal lesion size, chorioretinal pigmentation, macular elevation and media clarity. TTT uses 810-nm diode laser infrared radiation, which has no significant retinal phototoxicity. A parfocal laser delivery system is required to assure uniformity of irradiance across large diameter treatment spots. Relative contraindications for TTT include dense subretinal hemorrhage, prior focal photocoagulation and serous RPE detachment. Adverse events are rare, and include decreased vision and retinal arteriole occlusion. Randomized, prospective multi-center trials are underway to compare the results of TTT for occult CNV in age-related macular degeneration to the natural history of the disorder. Imaging, electrophysiologic or thermometric techniques may ultimately provide intra-operative or post-operative monitoring to assure the adequacy of TTT for CNV, despite the absence of ophthalmoscopically visible lesions.

Indocyanine green enhanced subthreshold diode-laser micropulse photocoagulation treatment of chronic central serous chorioretinopathy

PURPOSE

To assess the efficacy and safety of indocyanine green (ICG) dye-enhanced subthreshold diode-laser micropulse (SDM) photocoagulation in patients with chronic central serous chorioretinopathy (CCSC) with no spontaneous resolution 6 months after the onset of the disease.

STUDY DESIGN

Interventional prospective non-comparative case series of seven patients presenting with CCSC with well-defined active leaking sites (ALS) suitable for laser treatment and with serous neuroepithelial detachment persisting for 6 or more months.

METHODS

SDM treatment was performed 15 minutes after the injection of 25 mg of ICG in 2 cc of 5% glucose solution. ALS were treated with a series of 50 500-ms exposures separated by 500-ms pauses. Each 500-ms exposure delivered a train of 250 micropulses at 10% duty cycle and 500 mW power. ICG angiographic images were taken after the treatment without new ICG injection, to check for the presence of laser-induced spots of background hypofluorescence at the treated leakage sites.

RESULTS

Within 7-14 days after treatment, all the patients showed improved visual acuity and reduction of serous neuroepithelial detachment on OCT. No signs of laser lesions were visible at fundus examination and on fluorescein angiography. In a period ranging from 4 to 8 weeks, the neuroepithelial detachment was completely resolved in five patients and reduced in two patients. At the 12-month follow-up visits, no recurrence had occurred in the patients, with resolution of the serous neuro-epithelial detachment, and no worsening of the serous detachment or of VA was noted in the patients with incomplete recovery.

CONCLUSIONS

These preliminary results suggest that ICG dye-enhanced SMD photocoagulation appears to be an effective treatment, and can represent a viable approach for the management of CSCC with persistent serous neuroepithelial detachment. Post-treatment ICG angiography, without new ICG dye injection, can be used to verify the placement of the SDM laser applications.

Cyclophotocoagulation with the transscleral contact red 670-nm diode laser in the treatment of glaucoma

PURPOSE

To retrospectively evaluate the results of cyclophotocoagulation (CPC) with the transscleral contact red 670-nm diode laser in treating glaucoma.

METHODS

Cyclophotocoagulation was performed in 60 eyes of 60 patients with a mean age of 74 +/- 11 years (range 49-90 years). The treatment was delivered via a fibre-optic probe. The power per application was 430 mW. Exposure time was 10 seconds.

RESULTS

The mean overall follow-up time after the initial CPC was 26 +/- 20 months (range 3-75 months). Preoperative intraocular pressure (IOP) was 27 +/- 11 mmHg (n = 60). After one or more CPC treatments, mean IOP decreased to 20 +/- 7 mmHg (n = 51) at 1 month, 19 +/- 5 mmHg (n = 45) at 3 months, 18 +/- 5 mmHg (n = 29) at 6 months, 19 +/- 7 mmHg (n = 22) at 1 year, 18 +/- 7 mmHg (n = 16) at 2 years, 14 +/- 4 mmHg (n = 8) at 3 years, and 18 +/- 6 mmHg (n = 60) at the last follow-up. An IOP of 8-21 mmHg or a > 30% decrease in IOP was obtained in 33 of 41 eyes (80%) with baseline IOP > 21 mmHg at the last follow-up. Hypotonia (IOP < 8 mmHg) did not develop in any of the eyes studied.

CONCLUSIONS

Cyclophotocoagulation with the red 670-nm diode laser is an effective and well tolerated means of treating glaucoma.

Large-spot subthreshold infrared laser to treat diabetic macular edema

PURPOSE

To evaluate the efficacy of a large-spot subthreshold infrared laser protocol to treat diabetic maculopathy.

METHODS

In a prospective, fellow eye, controlled case series, all patients had clinically significant diabetic macular edema (DME) treated with a single application of subthreshold infrared (810 nm) laser. If bilateral disease was present, the fellow eye was treated with conventional macular laser. The study was to include 20 patients. Visual acuity and central macular thickness (CMT) measured by optical coherence tomography (OCT) were assessed in the study and fellow eyes at baseline and 6 months, and any changes were compared.

RESULTS

The 11th patient developed a choroidal infarct with subsequent profound loss of vision immediately after treatment. The study was terminated prematurely at this point. For the remaining 10 patients, there was a trend toward improvement in visual acuity in the study eye compared with the fellow eye at the 6-month follow-up (median change: +1.5 letters for study eye vs -6.5 letters for fellow eye; P = 0.08). There was also significant improvement in OCT-measured CMT in the study eye (mean decrease, 117 microm) compared with deterioration in OCT-measured CMT in the fellow eye (mean increase, 24 microm; P = 0.02).

CONCLUSION

This subthreshold infrared laser protocol led to improvement in OCT-measured CMT and stabilization of vision in most subjects. The current protocol is however unpredictable and should not be used in the treatment of DME without further modification.

Numerical modelling of conductive and convective heat transfers in retinal laser applications

The control of the temperature increase is an important issue in retinal laser treatments. Within the fundus of the eye heat, generated by absorption of light, is transmitted by diffusion in the retinal pigment epithelium and in the choroid and lost by convection due to the choroidal blood flow. The temperature can be spatially and temporally determined by solving the heat equation. In a former analytical model this was achieved by assuming uniform convection for the whole fundus of the eye. A numerical method avoiding this unrealistic assumption by considering convective heat transfer only in the choroid is used here to solve the heat equation. Numerical results are compared with experimental results obtained by using a novel method of noninvasive optoacoustic retinal temperature measurements in rabbits. Assuming global convection the perfusion coefficient was evaluated to 0.07 s(-1), whereas a value of 0.32 s(-1)--much closer to values found in the literature (between 0.28 and 0.30 s(-1))--was obtained when choroidal convection was assumed, showing the advantage of the numerical method. The modelling of retinal laser treatment is thus improved and could be considered in the future to optimize treatments by calculating retinal temperature increases under various tissues and laser properties.

Transpupillary thermotherapy in chinese patients with choroidal neovascularization secondary to age-related macular degeneration: emphasis on the influence of power setting

PURPOSE

To perform a safety and efficacy study of transpupillary thermotherapy (TTT) in Chinese patients with choroidal neovascularization (CNV) secondary to age-related macular degeneration (ARMD).

METHODS

In a prospective study, patients with subfoveal or juxtafoveal CNV secondary to ARMD underwent TTT with fixed treatment and follow-up protocols. From August 2002 to December 2004, 26 patients (27 eyes) completed > or =6 months of follow-up and were included in this report.

RESULTS

Fourteen eyes (52%) had improved or stable visual acuity (loss of <3 lines) and 13 eyes (48%) had vision loss of > or =3 lines. The serial mean visual acuity initially decreased during follow-up, then stabilized by 6 months. In the subgroup of occult or minimally classic CNV (20 eyes), 13 eyes (65%) had improved or stable vision. The major complication of TTT included laser-related retinal pigment epithelium (RPE) atrophy in 10 eyes (37%). Six eyes had mild RPE atrophy, 4 eyes had severe RPE-choroid atrophy (macular burn). Analysis of possible risk factors for macular burn showed that 3 eyes had to have the power amplified due to nuclear sclerosis, and 1 pseudophakic eye had regular power.

CONCLUSIONS

TTT in Chinese ARMD patients with occult or minimally classic CNV, according to our protocol, prevented severe vision loss in the majority of patients, but power amplification due to medium lens opacity induced RPE atrophy or burn in some patients.

Relationship between intensity of reflected light and temperature increase: assessment of fundus pigmentation for transpupillary thermotherapy

PURPOSE

To develop a new device for measuring reflected light during diode-laser irradiation in transpupillary thermotherapy (TTT) and to assess the correlation between fundus pigmentation, the measured intensity of reflected light, and the increase in fundus temperature.

METHODS

We developed a device to measure reflected light by modifying a slit-lamp-mounted 810-nm diode-laser delivery system used clinically for TTT. The diode laser was used to irradiate test charts with various degrees of reflectance in in vitro experiments, and the fundus of nonpigmented or pigmented rabbits in in vivo experiments; then, the intensity of the reflected light and the temperature increase at the target were measured. The retinal sections were also examined histologically.

RESULTS

There was a significant negative correlation between the intensity of the reflected light and the temperature increase in the target that depended on the degree of reflectance of the charts or the pigmentation of the rabbit eyes. On histopathologic examination, the extent of the changes in the irradiated retina after TTT was clearly different between pigmented and nonpigmented rabbits.

CONCLUSIONS

Correlations between fundus pigmentation, the intensity of reflected light during diode-laser irradiation, and the temperature increase in TTT were demonstrated in vitro and in vivo. Our results suggest that measurement of the intensity of reflected light should be helpful for modulating the laser power in TTT according to the degree of fundus pigmentation.

Is transpupillary thermotherapy applicable to the treatment of age-related macular degeneration with pigment epithelial detachment?

The cause of pigment epithelial tears at the edge of a pigment epithelial detachment (PED) following transpupillary thermotherapy (TTT) in eyes with a PED associated with age-related macular degeneration has not been conclusively determined. We have treated two eyes that had a PED with TTT. A pigment epithelial tear developed in one eye but not in the other. Our findings suggest that pigment epithelial tears are probably related to the shape of the PED, and TTT should not be applied to a balloon-shaped PED.

Is transpupillary thermotherapy applicable to the treatment of age-related macular degeneration with pigment epithelial detachment?

The cause of pigment epithelial tears at the edge of a pigment epithelial detachment (PED) following transpupillary thermotherapy in eyes with associated age-related macular degeneration is unclear. We have treated 2 eyes which had a PED with TTT. Our findings suggest pigment epithelial tears are probably related to the shape of the PED and TTT should not applied to a balloon-shaped PED.

Modulation of Ku70/80, Clusterin/ApoJ Isoforms and Bax Expression in Indocyanine-Green-Mediated Photo-Oxidative Cell Damage

PURPOSE

In order to characterize the biological effects and molecular mechanism underlying indocyanine-green (ICG)-mediated photo-oxidative cell damage, human cultured retinal pigmented epithelium (RPE) cells preloaded with ICG were exposed to 810-nm laser irradiation. Cell viability and death induction were examined, as well as the modulation of proteins involved in cell death and DNA repair.

METHODS

ARPE-19 cells preloaded with 100 microM ICG were irradiated using continuous and micropulsed 810-nm laser for the dye photoactivation, and cell viability and apoptosis were evaluated. The expression and subcellular localization of Bax, Ku70, Ku80 and clusterin/ApoJ were analyzed by immunocytochemistry and Western blot.

RESULTS

ICG photoactivation induced apoptosis in RPE cells. The micropulsed laser irradiation induced a higher percentage of cell killing as compared to continuous wave. Cell killing was inhibited by sodium azide, suggesting the involvement of reactive oxygen species in the laser-induced cell damage. Bax was strongly induced after 4 and up to 24 h of treatment. The nuclear proapoptotic isoform of clusterin/ApoJ was selectively upregulated after 24 h of treatment. The DNA repair machinery was upregulated after 4 and up to 24 h.

CONCLUSION

These data elucidate some molecular mechanisms involved in cell death induced by ICG photosensitization. The increase and relocalization of Bax into the mitochondria and the upregulation and translocation of the proapoptotic isoform of clusterin/ApoJ in the nucleus demonstrated the involvement of these proteins in the photo-oxidative cell death pathway. These data point out new molecular targets and suggest potential applications in the therapy of the retinal diseases that could benefit by selective RPE treatment.

Value-based medicine and interventions for macular degeneration

PURPOSE OF REVIEW

The aim of this article is to review the patient value conferred by interventions for neovascular macular degeneration.

RECENT FINDINGS

Value-based medicine is the practice of medicine based upon the patient value (improvement in quality of life and length of life) conferred by an intervention. For ophthalmologic interventions, in which length-of-life is generally unaffected, the value gain is equivalent to the improvement in quality of life. Photodynamic therapy delivers a value gain (improvement in quality of life) of 8.1% for the average person with classic subfoveal choroidal neovascularization, while laser photocoagulation for the same entity confers a 4.4% improvement in quality of life. Preliminary data suggest the value gain for the treatment of occult/minimally classic choroidal neovascularization with ranibizumab is greater than 15%. The average value gain for statins for the treatment of hyperlipidemia is 3.9%, while that for the use of biphosphonates for the treatment of osteoporosis is 1.1% and that for drugs to treat benign prostatic hyperplasia is 1-2%.

SUMMARY

Interventions, especially ranibizumab therapy, for neovascular macular degeneration appear to deliver an extraordinary degree of value compared with many other interventions across healthcare.